Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.30	9.260%	$201.3662	$201.37	$201.35	$201.40
Purchase #2	$241.28	9.720%	$264.7324	$264.73	$264.75	$264.70
Purchase #3	$19.46	10.602%	$21.5231	$21.52	$21.50	$21.50
Purchase #4	$142.60	6.402%	$151.7293	$151.73	$151.75	$151.70
Purchase #5	$185.39	8.305%	$200.7866	$200.79	$200.80	$200.80
Purchase #6	$131.33	7.530%	$141.2191	$141.22	$141.20	$141.20
Purchase #7	$109.59	6.629%	$116.8547	$116.85	$116.85	$116.90
7 purchase totals =	$1,013.95		$1,098.2114	$1,098.21	$1,098.20	$1,098.20